Process for improving stability and engine cleanliness characteristics of petroleum fractions



2,567,174 CLEANLINESS 'CHARACTERISTICS OF PETROLEUM FRACTIONS Sept. 11, 1951 E. ARUNDALE EIAL FOR IMPROVING STABILITY AND ENGINE PROCESS Filed Jan. 24, 1949 FurzN cE HEAT Excu-wmenzw- Somuaz UNSTAbLE NAPHTHA Fommm-wna FRACT louAToz,

t- 1 EAM I boTToms Era-in I dose obs?- Haw'ortl z a Qrurzda Z 5 21/ fl7 vlllwo/C lbb'ofrzeg Patented Sept. ll, 1951 ENGINE CLEANLINESS CHARACTERISTICS OF PETROLEUM FRACTIONS Ewing Arnndalev and Joseph P. Haworth, West iield, N. 1., asaignors to Standard Oil Development Company, a corporation of Delaware Application January e4, 1949, Serial a... 72,416

The present invention is concerned with the production of high quality petroleum oil products. The invention is more particularly concerned with the treatment of cracked petroleum oil fractions boiling below about 700 F. (370' C.) with an aldehyde at elevated temperatures in the absence of an added catalyst. In accordance with the present invention thermally or catalytically cracked petroleum hydrocarbons, especially those boiling below about 700 F., are contacted with an aldehyde, preferably formaldehyde at elevated temperatures and under conditions to secure a minimum degradation of the stock being treated.

It is well known in the art toreflne petroleum fractions for the production of high quality gasolines, kerosenes, and diesel fuels by various procedures. For example, it is known to treat petroleum fractions boiling in the motor fuel boiling range with sulfuric acid and with various other reagents. While the use of sulfuric acid pros Clainu. (Cl. 196-35) means of pump 3 is passed through aheat exchange zone 4 and is introduced into heatin zone 5. In accordance with the present invention the mixture in heating zone or furnace l is heated to a temperature in the range from about 100 C. to 400 C. The heated stock is withdrawn from zone I by means of line i at a temperature assumed to be about 250 C. and introduced into zone I. wherein the time the heated fraction is held at the desired temperature is controlled.

The petroleum fraction is withdrawn from zone I by means of line I and preferably recycled through zone 5 and then introduced into distillation zone ID by means of line 9. Temperature and pressure conditions are controlled in distillation zone ll so as to remove overhead by means of duces a satisfactory product,in many operations,

particularly when the feed 011- comprises a cracked stock, a relatively high polymerization loss results. Furthermore, when theconcentration of undesirable constituents is relatively high, it is necessary to use rather large quantities of acid which necessitates further refining of the acid treated oil after removal of the treating acid. In addition the acid must be recovered and reconcentrated or otherwise restored. It has now ;been discovered that, providing elevated temperatures are utilized, unexpected and desirable results are secured if petroleum oils are contacted with an aldehyde, preferably formaldehyde, in the absence of added catalysts.

The process of the present invention may be readily understood by r f ren o e dr win illustrating one embodiment of the same. For the purpose of illustration it is assumed the feed comprises a naphtha which boils inthe range from about 150 F. to 430 F. (66 C. to 221? C.) and is introduced into the system b means of line i. Formaldehyde as an aqueous solution is introduced by means of line 2. The mixture by line H the relatively low boiling hydrocarbon constituents and to remove as a bottoms by means of line I! the small amount of relatively high boiling hydrocarbon constituents. Steam may be introduced if desired into zone It by means of line ll.

'il'hc fraction removed overhead by means of line H is passed through condensing zone i4 and introduced into separation zone It. Uncondensed gases are withdrawn from the system by means of line it while the condensed distillate is removed from zone It by means of line H. Water may be withdrawn from zone It by means of line II. The product withdrawn by means of line I1 is segregated into two streams, one of which is returned as reflux by means of line i9, while the other is withdrawn as a product stream by means of line 20 and further refined as desired. The product can be subsequently washed with water or dilute caustic soda solution. Suitable oxidation inhibitors and/or other additives can also be incorporated into the finished product.

As another embodiment of this invention it is possible to add the formaldehyde as an aqueous solution or as a gas to the cracked hydrocarbon feed entering a distillation zone or to the distillate line leaving this zone. In other words it is possible to add formaldehyde at any point in a re- 3 ilnery process where a cracked stock is to be heated or is being heated at an elevated temperature.

The invention may be more fully understood by the following examples further illustrating thesame.

EXAMPLE 1.

toms (51.5% of thetotal) was cooled, filtered.

and used as a feed stock in the various operations presented below.

In these operations the hydrocarbon feed was heated at a given temperature for a given time both in the presence and in the absence of vary in: quantities of formaldehyde. The oil was cooled and the water layer (if any) removed. The products were washed with 20 volume per cent of water and then with 20 volume per cent of a 3% sodium hydroxide solution. The caustic was removed and the products rerun to a 400 F. end point. The distillates were water washed, filtered, and inhibited with mD'di-secondarybutyl-paraphenylene-diamine to the extent of one pound per' 5000 gallons. The results are 4 fluoborate deposit factor reduced as the temperature of contact is increased. (The lower values of this deposit factor indicate cleaner gasolines.)

The diazonium fluoborate deposit factor is an index of the engine cleanliness characteristics of a motor fuel.

This test utilizes the coupling reaction which takes place between diazotised p-nitro aniline and certain unsaturated compounds (which causeengine fouling) to form a colored compound. Intensity of color formed aftera given time interval is taken as an index of the deposit forming compounds present. In running the test the fraction of the sample boiling over 275' F. and puriiled by treatment with dilute acid and alkali and steam distillation to 3% bottoms is used. A known quantity of this fraction is added to a solution of n-nitroaniline dlazonium fluoborate (NOzCeH4N=NBF4) .in acetone and the optical density measured at intervals in a Helllgc-Diller emission photometer. The optical density is plotted against time and the value after 20 minuta read from the curve. The optical density multiplied by the ratio of the fraction boiling over 275 F. to the whole sample gives the diazonium iiuoborate deposit factor.

EXAMPLE 2 In this series of operations the whole 90-10 From the above it is apparent that treatment and the copper dish gum content and diazonium listed in the following table: so vol. thermal naphtha-heavy catalytic naphtha Tasu I mt 1 ASTM er en Diazonium B .mtmmt Bottoms Break- Bromine 3w Fluoborate Temp., Time, (Based 33% Gum 4 iC. 111E 3 1 u Itsotor EFFECT CF FOBMALDEBYDE CONCENTRATION L".-- Feed itself (no CHgO)--- 1 6.8 196 19.4 222 61.8 3---..- 1 C1120.-- 1W 1 0.0 17.8 174 38.0 0.-.--- CHaO 100 1 8. 2 326 16. 7 176 19. 3 ID... a CHgO 190 1 8.6 330 17.0 134 13.3

EFFECT OF TEMPERATURE AND CONTACT TIME 1 7.8 225 18. 6 231 45. 9 1 8.8 $0 17. 6 145 27.8 l 8. 2 325 16. 7 176 19. 3 190 K 8. 2 280 .14. 3 193 24. 8 210 1 8.4 390 15.0 132 0. 6 210 X 7. 2 360 15. 0 139 10. 7 230 1 8. 8 435 16. 2 11.0 6. 2 260 1 10. 2 650 14. 6 90 6. 3

1 Material boiling above 400 F. I ASTM rocedure designation D 526-46. glam/{30x6 gm.

g. cc. I Formaldehyde em loyed as a 377 by weight "Formula" solution. Formaldeh e concentration expressed as per cent ydrons iormald hyde by weight based on hydrocarbon charged. yd

blend (without topping) was employed. This blend possessed a bromine number of 34 0.8. Br/gm and a final boiling point of 430 F. This gasoline feed was heated in the presence and absence of varying quantities of 37% Formalin solution at temperatures between 190-270 C. The products were cooled, the water layer separated and the oil layer water washed, caustic washed, and rerun to a 400 F. vapor temperature. The distillate was water washed. filtered, inhibited as in Example 1, and inspected. The data are ven in Table II.

I TABL!i II p Refining a 90-10 polufite per cent thermalcatalvtic naphtha blend with formaldehyde .thiermal reactiono oatnlysttormaldehyde concentration as per centbu weight on gasoline Contact w lziiazo- :ASTM I P01011111 c 1 mm Treatment Bottoms Break DE:

'Iemp., -Time. 0n Gum 7 C. Hrs. lieed F8822;

132-.--*ater+fia0liwmhedandrcrun 40 .420 205 140.2 100... Feedbyitsell. 100 1 5.5 21.0 100 145.8 as d 210 1 4.1 25.2 240 134.2-

355 58.4 2:10 1 0.1 1.2- 305 50.s 23 1 I 1.2 --5.a1 510 5a1 250 1 1.1 3.02 500 241 250 14 5.2 5.24 300 40.1 250 14 y 5.2 10.5 345 48.7 100 ;1 es 011 420' a 20.1 210 1 5.1 431 485- 11.2 no 1 1.0 3.21 086 24. 230 0.0 2.53 420 03.2 210 5.0 5.02 440 54.2 25 1 0.1 2.50 000 40.0 v 250 14 1.1 4.01 015 54.1; -.do. 250 4 1.2 ass 555 3214 .....do 270 l 7.6 1.!) 51) 56.4 180--. 2.6 Vol. Per Cent Water alone. 230 1 4.0 34.2 415 98.0 112... 2.12% Paraformaldehyde 200 1 0.1 4.20 515 4111 1 2.12%+2.0Vol.PerCentWater. 220 1 as 2.14 505 22.2 173--- 5.1 Methylal 230 1 0.5 16.8 325 43.5 118... 5.1 .,+2.e v01. Per Cent Water 2:10 1 5.1 8.84 200 40.0 114.-- 2. ,Trlorane' 2:40 1 0.5 10.4 215 51.1 170... 2.0%+2.0 Vol. Per Cent Water 230 1 0.4 21.8 336 44.3

mm boiling above 400! 5 By weight based on gasolino equlvalent t412% anhydrous formaldehyde.

The results show that the treatment of cracked gasollnes with formaldehyde at temperatures between 190-270" C. produces a definite reduction in the diazonium fluoborate deposit factor, an

improvement in oxidation stability,.and a reduction in gum content which cannot be obtained by heating the gasoline alone under the same conditions.

The present invention is generally concerned with the use of a relatively small amount of an aldehyde, preferably formaldehyde for the treatmentof petroleum hydrocarbons boiling below about 700 "1". The process is. particularly applicable-for the treatment of petroleum hydrocarbons secured from either thermal or catalytic cracking or reforming operations. In accordance with the present invention, high quality gasolines are secured by contacting thermally or catalytically cracked distillates with formaldehyde at elevated temperatures in the absence of added catalysts. In general; it is preferred that the feed stocks have a bromine number of 'at least 10 Cg Br/gram. These cracked stocks can be secured either from gas oil streams, reduced crude streams, whole crude streams, or other refinery operations.

The temperature of treatment is in the range from 100 C. to 400 0., preferably in the range from 190C. to 270 C. Thetime of contact may vary appreciably depending upon the temperature and the character of the feed stock, but

is generally in the range from about 5 to 60 minutes; The operating-pressure may be as high m 1000# psig. The aldehyde used is preferably formaldehyde present in a concentration from about V to 5% (anhydrous basis) by weight based on the oil being treated. The formaldehyde concentration will vary depending on the unsaturation and composition of the hydrocarbons feed. The formaldehyde is preferably-added as the 37% (by weight) aqueous "Formalin soluformaldehyde, trioxane, methylal, other aldehydes -(acetaldehyde, acrolein, etc.) ketones, organic acids, phenols or cresols, carbon monoxide, etc. can also be employed in the presence or absence of water. Any combination which yields formaldehyde, as for example which yields formaldehyde on heating'or in the presence of water, is satisfactory. Rerunning of the treated product is-consldered desirable in order to obtain finished products of the highest quality, although extracthan of the higher boiling condensation products with certain solvents or solid adsorbents can be employed. Y r

The process of thisinvention is particularly effective in improving motor gasoline quality, however, it is also applicable for improving the stability of heating oils, kerosenes, diesel fuel, light naphthas and other petroleum fractions.

Having described the invention, it is claimed;

1. Process for the refining of petroleum fractions boiling below about 370 C. to improve stability and engine cleanliness which comprises contacting said petroleum fraction with a treating agent consisting solely of formaldehyde at a rnmperature in the range of about 100. C. to

2. Process as defined by claim 1 in which said petroleum fraction includes constituents derived from cracking processes.

3. Process defined by claim 1 in which the temperature of contact is in the range from about 190 'C. to 270 C.

4. Process defined by claim 1 in which the concentration of the formaldehyde is about 0.25 to 5% based upon the weight of the petroleum fraction being contacted.

5. Process for refining of cracked petroleum fractions boiling-below about 370 C. to improve stability and engine cleanliness which comprises a treating agent consisting solely of 75 formaldehyde to said petroleum fraction, heating tlonalthough other treating agents such as para- 7 tbe'petroleum fraction to a. temperature in the range from about 100 to 400 C. and holding said petroleum fraction at this temperature for a time periodof from 5 to 60 minutes, then segregating the treated fraction from higher boiling constituents.

6. Process for the production of high quality motor fuels having improved engine cleanliness characteristics which comprises vaporizing a pctroleum fraction boiling below about 215 C., and adding to said petroleum fraction while the same is in a vaporous state a relatively small percent of formaldehyde as the sole treating agent, then thereafter separating the treated fraction from higher boiling constituents.

ERVING ARUNDALE. JOSEPH P. HAWORTH.

8 REFERENCES crmn The following references are of record in the tile of this patent:

UNITED STATES PATENTS OTHER REFERENCES Ormandy et al. J. I. P. 'I., 10, 99 and 100. 

1. PROCESS FOR THE REFINING OF PETROLEUM FRACTIONS BOILING BELOW ABOUT 370 C. TO IMPROVE STABILITY AND ENGINE CLEANLINESS WHICH COMPRISES CONTACTING SAID PETROLEUM FRACTION WITH A TREATING AGENT CONSISTING SOLELY OF FORMALDEHYDE AT A 